1. Field of the Invention
The present invention relates to an inspecting apparatus which magnifies and is used to inspect substrates of semiconductor devices, such as those of a semiconductor wafer and a liquid crystal.
Priority is claimed on Japanese Patent Application No. 2004-076267, filed Mar. 17, 2004, the content of which is incorporated herein by reference.
2. Description of Related Art
In forming a device pattern on a surface of a semiconductor device, when manufacturing a semiconductor device, defects such as adhesion of foreign substances, and defects in pattern and abnormalities in size, may occur, and hence it is necessary to identify the defects. Concretely, visual examination is performed on the entirely substrate, and inspections using a line sensor are conducted, and a defective part is detected. An inspecting apparatus (observing apparatus) equipped with a function which performs a magnifying inspection of the surface of a semiconductor wafer is used for identifying these defects.
Plural objective lenses, each having a different magnifying power, are disposed in the inspecting apparatus. In the case in which magnifying inspection of the circuit pattern formed on the surface of a semiconductor wafer is performed, an arbitrary objective lens is inserted into an inspection light path, and is located opposed to the inspection location of the surface of the semiconductor wafer. Here, because the focal length of an objective lens decreases as the magnifying power of the objective lens increases, in the case in which the objective lens having a high magnifying power is used, the space between the objective lens and the semiconductor wafer must be decreased. That is, for example, in the case in which an observation at a high magnifying power and of a high resolution is performed using ultraviolet light for illumination, an objective lens for ultraviolet light is used, but the working distance (WD, free working distance) of this objective lens is only 0.2 to 0.3 mm. It should be noted that in changing the magnifying observation position of the semiconductor wafer surface, the objective lens is moved in the direction along the surface of the semiconductor wafer.
In addition, in the manufacturing process of a semiconductor device, cambering and bending of a semiconductor wafer occur. For this reason, when the objective lens is moved along the surface of the semiconductor wafer, the space between the objective lens and the semiconductor wafer may become narrower than the WD of the objective lens.
Therefore, as a conventional inspecting apparatus, for example, Japanese Unexamined Patent Application, First Publication No.2001-134760 discloses one which is equipped with distance sensors for measuring the distance from the objective lens to the semiconductor wafer, so as to maintain the space between the objective lens and the semiconductor wafer constant, in order to avoid contact of the objective lens with the semiconductor wafer.
Moreover, conventional inspecting apparatuses include one which is equipped with an entire surface chucking plate which performs vacuum chucking of the entire back surface of a semiconductor wafer as a loading stage on which a semiconductor wafer is disposed, such that the cambering of the semiconductor wafer and bending might be corrected using the vacuum chucking power.